1. Field of the Invention
The present invention relates to an automatic engine stop-start system, and in particular to an automatic engine stop-start system which automatically stops or starts an engine in case predetermined conditions are fulfilled in a vehicle such as a motorcar.
2. Prior Art
Generally, when a vehicle stops at a crossing in the street or the like, idling the engine of the vehicle will consume a certain amount of fuel and decrease the fuel consumption rate of the engine.
Accordingly, there has been proposed an automatic engine stop-start system which automatically stops the engine to reduce the fuel consumption thereof during temporary stops every time such a predetermined condition (stop condition) that the car has stopped is fulfilled and which then automatically starts or restarts the engine every time another predetermined condition (start condition) is fulfilled.
The stop condition and the start condition in such an automatic engine stop-start system are schematically shown in FIGS. 1A and 1B, respectively.
The stop condition requires four items shown in FIG. 1A such that:
(1) Car speed is approximately 0 Km/h; PA1 (2) Engine rotating speed is below 800 rpm; PA1 (3) Gear position is neutral; and, PA1 (4) Clutch pedal is stepped on or depressed. PA1 (5) Cooling water temperature of the engine is equal to or above 40.degree. C.; PA1 (6) Air pressure is equal to or above 64 KPa; PA1 (7) A car speed higher than 10 Km/h after the initiation of the system is once detected; and, PA1 (8) No fault is found by self-diagnosis. PA1 (1) Engine speed is 0 rpm; PA1 (2) Gear position is neutral; PA1 (3) Clutch is engaged.
Additionally, the following items should be preferably included in the stop condition shown by dotted lines in FIG. 1A such that:
Specifically, the condition for automatic engine stop is that (1) a car is stopped, (2) the engine is idling, (3) the gear position is neutral, (4) no clutching operation is made, and preferably that (5) the engine is warmed up, (6) the air pressure of the air tank for the air cylinder (see FIG. 4) is sufficient for the automatic engine stop, (7) it has been confirmed that the car has started at least once after the engine key had been switched on, and (8) no fault is found.
When the above stop condition is fulfilled, the intake shutter (see FIG. 4) is shut by the air cylinder to stop the air suction of the engine whereby the engine is automatically stopped to prevent the fuel from being uselessly consumed and to reduce exhaust gas or noise.
On the other hand, the condition for restarting (hereinafter referred to simply as starting) the engine after the engine has been stopped on the basis of the above-noted stop condition requires three well-known items shown in FIG. 1B such that:
It is, however, disadvantageous that although the above prior art automatic engine stop-start system can be mounted on a manual transmission (MT) car, it can not be adapted to an automatic transmission (AT) car.